* Takes a set of objects, formats them, then inserts the formatted * strings into the pattern at the appropriate places. *
* Here are some examples of usage: * Example 1: *
* \code
* UErrorCode success = U_ZERO_ERROR;
* GregorianCalendar cal(success);
* Formattable arguments[] = {
* 7L,
* Formattable( (Date) cal.getTime(success), Formattable::kIsDate),
* "a disturbance in the Force"
* };
*
* UnicodeString result;
* MessageFormat::format(
* "At {1,time} on {1,date}, there was {2} on planet {0,number}.",
* arguments, 3, result, success );
*
* cout << "result: " << result << endl;
* //
* Typically, the message format will come from resources, and the
* arguments will be dynamically set at runtime.
* * Example 2: *
* \code
* success = U_ZERO_ERROR;
* Formattable testArgs[] = {3L, "MyDisk"};
*
* MessageFormat* form = new MessageFormat(
* "The disk \"{1}\" contains {0} file(s).", success );
*
* UnicodeString string;
* FieldPosition fpos = 0;
* cout << "format: " << form->format(testArgs, 2, string, fpos, success ) << endl;
*
* // output, with different testArgs:
* // output: The disk "MyDisk" contains 0 file(s).
* // output: The disk "MyDisk" contains 1 file(s).
* // output: The disk "MyDisk" contains 1,273 file(s).
* delete form;
* \endcode
*
*
* The pattern is of the following form. Legend:
*
* \code
* {optional item}
* (group that may be repeated)*
* \endcode
*
* Do not confuse optional items with items inside quotes braces, such
* as this: "{". Quoted braces are literals.
*
* \code
* messageFormatPattern := string ( "{" messageFormatElement "}" string )*
*
* messageFormatElement := argument { "," elementFormat }
*
* elementFormat := "time" { "," datetimeStyle }
* | "date" { "," datetimeStyle }
* | "number" { "," numberStyle }
* | "choice" "," choiceStyle
*
* datetimeStyle := "short"
* | "medium"
* | "long"
* | "full"
* | dateFormatPattern
*
* numberStyle := "currency"
* | "percent"
* | "integer"
* | numberFormatPattern
*
* choiceStyle := choiceFormatPattern
* \endcode
*
* If there is no elementFormat, then the argument must be a string,
* which is substituted. If there is no dateTimeStyle or numberStyle,
* then the default format is used (e.g. NumberFormat.getInstance(),
* DateFormat.getDefaultTime() or DateFormat.getDefaultDate(). For
* a ChoiceFormat, the pattern must always be specified, since there
* is no default.
* * In strings, single quotes can be used to quote the "{" sign if * necessary. A real single quote is represented by ''. Inside a * messageFormatElement, quotes are [not] removed. For example, * {1,number,$'#',##} will produce a number format with the pound-sign * quoted, with a result such as: "$#31,45". *
* If a pattern is used, then unquoted braces in the pattern, if any, * must match: that is, "ab {0} de" and "ab '}' de" are ok, but "ab * {0'}' de" and "ab } de" are not. *
* The argument is a number from 0 to 9, which corresponds to the * arguments presented in an array to be formatted. *
* It is ok to have unused arguments in the array. With missing * arguments or arguments that are not of the right class for the * specified format, a failing UErrorCode result is set. *
* For more sophisticated patterns, you can use a ChoiceFormat to get * output such as: *
* \code
* UErrorCode success = U_ZERO_ERROR;
* MessageFormat* form = new MessageFormat("The disk \"{1}\" contains {0}.", success);
* double filelimits[] = {0,1,2};
* UnicodeString filepart[] = {"no files","one file","{0,number} files"};
* ChoiceFormat* fileform = new ChoiceFormat(filelimits, filepart, 3);
* form->setFormat(1, *fileform); // NOT zero, see below
*
* Formattable testArgs[] = {1273L, "MyDisk"};
*
* UnicodeString string;
* FieldPosition fpos = 0;
* cout << form->format(testArgs, 2, string, fpos, success) << endl;
*
* // output, with different testArgs
* // output: The disk "MyDisk" contains no files.
* // output: The disk "MyDisk" contains one file.
* // output: The disk "MyDisk" contains 1,273 files.
* \endcode
*
* You can either do this programmatically, as in the above example,
* or by using a pattern (see ChoiceFormat for more information) as in:
*
* \code
* form->applyPattern(
* "There {0,choice,0#are no files|1#is one file|1
*
* [Note:] As we see above, the string produced by a ChoiceFormat in
* MessageFormat is treated specially; occurances of '{' are used to
* indicated subformats, and cause recursion. If you create both a
* MessageFormat and ChoiceFormat programmatically (instead of using
* the string patterns), then be careful not to produce a format that
* recurses on itself, which will cause an infinite loop.
*
* [Note:] Formats are numbered by order of variable in the string.
* This is [not] the same as the argument numbering!
*
* \code
* For example: with "abc{2}def{3}ghi{0}...",
*
* format0 affects the first variable {2}
* format1 affects the second variable {3}
* format2 affects the second variable {0}
* \endcode
*
* and so on.
*/
class U_I18N_API MessageFormat : public Format {
public:
enum EFormatNumber { kMaxFormat = 10 };
/**
* Construct a new MessageFormat using the given pattern.
*
* @param pattern Pattern used to construct object.
* @param status Output param to receive success code. If the
* pattern cannot be parsed, set to failure code.
* @stable
*/
MessageFormat(const UnicodeString& pattern,
UErrorCode &status);
/**
* Constructor that allows locale specification.
* @param pattern Pattern used to construct object.
* @param newLocale The locale to use for formatting dates and numbers.
* @param status Output param to receive success code. If the
* pattern cannot be parsed, set to failure code.
* @stable
*/
MessageFormat(const UnicodeString& pattern,
const Locale& newLocale,
UErrorCode& success);
/**
* Copy constructor.
* @stable
*/
MessageFormat(const MessageFormat&);
/**
* Assignment operator.
* @stable
*/
const MessageFormat& operator=(const MessageFormat&);
/**
* Destructor.
* @stable
*/
virtual ~MessageFormat();
/**
* Clone this Format object polymorphically. The caller owns the
* result and should delete it when done.
* @stable
*/
virtual Format* clone(void) const;
/**
* Return true if the given Format objects are semantically equal.
* Objects of different subclasses are considered unequal.
* @stable
*/
virtual UBool operator==(const Format& other) const;
/**
* Sets the locale. This locale is used for fetching default number or date
* format information.
* @stable
*/
virtual void setLocale(const Locale& theLocale);
/**
* Gets the locale. This locale is used for fetching default number or date
* format information.
* @stable
*/
virtual const Locale& getLocale(void) const;
/**
* Apply the given pattern string to this message format.
*
* @param pattern The pattern to be applied.
* @param status Output param set to success/failure code on
* exit. If the pattern is invalid, this will be
* set to a failure result.
* @stable
*/
virtual void applyPattern(const UnicodeString& pattern,
UErrorCode& status);
/**
* Gets the pattern. See the class description.
* @stable
*/
virtual UnicodeString& toPattern(UnicodeString& result) const;
/**
* Sets formats to use on parameters.
* See the class description about format numbering.
* The caller should not delete the Format objects after this call.
* @draft HSYS: possible semantic change on limitation of the size of array
*/
virtual void adoptFormats(Format** formatsToAdopt, int32_t count);
/**
* Sets formats to use on parameters.
* See the class description about format numbering.
* @draft HSYS: possible semantic change on limitation of the size of array
*/
virtual void setFormats(const Format** newFormats,int32_t cnt);
/**
* Sets formats individually to use on parameters.
* See the class description about format numbering.
* The caller should not delete the Format object after this call.
* @draft HSYS: possible semantic change on limitation of the size of array
*/
virtual void adoptFormat(int32_t formatNumber, Format* formatToAdopt);
/**
* Sets formats individually to use on parameters.
* See the class description about format numbering.
* @stable
*/
virtual void setFormat(int32_t variable, const Format& newFormat);
/**
* Gets formats that were set with setFormats.
* See the class description about format numbering.
* @draft HSYS: possible semantic change on limitation of the size of array
*/
virtual const Format** getFormats(int32_t& count) const;
/**
* Returns pattern with formatted objects. Does not take ownership
* of the Formattable* array; just reads it and uses it to generate
* the format string.
*
* @param source An array of objects to be formatted & substituted.
* @param result Where text is appended.
* @param ignore No useful status is returned.
* @stable
*/
UnicodeString& format( const Formattable* source,
int32_t count,
UnicodeString& result,
FieldPosition& ignore,
UErrorCode& success) const;
/**
* Convenience routine. Avoids explicit creation of
* MessageFormat, but doesn't allow future optimizations.
* @stable
*/
static UnicodeString& format( const UnicodeString& pattern,
const Formattable* arguments,
int32_t count,
UnicodeString& result,
UErrorCode& success);
/**
* Format an object to produce a message. This method handles
* Formattable objects of type kArray. If the Formattable
* object type is not of type kArray, then it returns a failing
* UErrorCode.
*
* @param obj The object to format
* @param toAppendTo Where the text is to be appended
* @param pos On input: an alignment field, if desired.
* On output: the offsets of the alignment field.
* @param status Output param filled with success/failure status.
* @return The value passed in as toAppendTo (this allows chaining,
* as with UnicodeString::append())
* @stable
*/
virtual UnicodeString& format(const Formattable& obj,
UnicodeString& toAppendTo,
FieldPosition& pos,
UErrorCode& status) const;
/**
* Redeclared Format method.
* @stable
*/
UnicodeString& format(const Formattable& obj,
UnicodeString& result,
UErrorCode& status) const;
/**
* Parses the string.
*
* Caveats: The parse may fail in a number of circumstances. For
* example:
*
* If one of the arguments does not occur in the pattern.
*
* If the format of an argument is loses information, such as with
* a choice format where a large number formats to "many".
*
* Does not yet handle recursion (where the substituted strings
* contain {n} references.)
*
* Will not always find a match (or the correct match) if some
* part of the parse is ambiguous. For example, if the pattern
* "{1},{2}" is used with the string arguments {"a,b", "c"}, it
* will format as "a,b,c". When the result is parsed, it will
* return {"a", "b,c"}.
*
* If a single argument is formatted twice in the string, then the
* later parse wins.
*
* @param source String to be parsed.
* @param status On input, starting position for parse. On output,
* final position after parse.
* @param count Output param to receive size of returned array.
* @result Array of Formattable objects, with length
* 'count', owned by the caller.
* @stable
*/
virtual Formattable* parse( const UnicodeString& source,
ParsePosition& status,
int32_t& count) const;
/**
* Parses the string. Does not yet handle recursion (where
* the substituted strings contain {n} references.)
*
* @param source String to be parsed.
* @param count Output param to receive size of returned array.
* @param status Output param to receive success/error code.
* @result Array of Formattable objects, with length
* 'count', owned by the caller.
* @stable
*/
virtual Formattable* parse( const UnicodeString& source,
int32_t& count,
UErrorCode& status) const;
/**
* Parse a string to produce an object. This methods handles
* parsing of message strings into arrays of Formattable objects.
* Does not yet handle recursion (where the substituted strings
* contain %n references.)
*
* Before calling, set parse_pos.index to the offset you want to
* start parsing at in the source. After calling, parse_pos.index
* is the end of the text you parsed. If error occurs, index is
* unchanged.
*
* When parsing, leading whitespace is discarded (with successful
* parse), while trailing whitespace is left as is.
*
* See Format::parseObject() for more.
*
* @param source The string to be parsed into an object.
* @param result Formattable to be set to the parse result.
* If parse fails, return contents are undefined.
* @param parse_pos The position to start parsing at. Upon return
* this param is set to the position after the
* last character successfully parsed. If the
* source is not parsed successfully, this param
* will remain unchanged.
* @return A newly created Formattable* object, or NULL
* on failure. The caller owns this and should
* delete it when done.
* @stable
*/
virtual void parseObject(const UnicodeString& source,
Formattable& result,
ParsePosition& parse_pos) const;
public:
/**
* Returns a unique class ID POLYMORPHICALLY. Pure virtual override.
* This method is to implement a simple version of RTTI, since not all
* C++ compilers support genuine RTTI. Polymorphic operator==() and
* clone() methods call this method.
*
* @return The class ID for this object. All objects of a
* given class have the same class ID. Objects of
* other classes have different class IDs.
* @stable
*/
virtual UClassID getDynamicClassID(void) const;
/**
* Return the class ID for this class. This is useful only for
* comparing to a return value from getDynamicClassID(). For example:
*
* . Base* polymorphic_pointer = createPolymorphicObject();
* . if (polymorphic_pointer->getDynamicClassID() ==
* . Derived::getStaticClassID()) ...
*
* @return The class ID for all objects of this class.
* @stable
*/
static UClassID getStaticClassID(void) { return (UClassID)&fgClassID; }
private:
static char fgClassID;
static NumberFormat* fgNumberFormat;
// fgNumberFormat is held in a cache of one.
static NumberFormat* getNumberFormat(UErrorCode &status); // call this function to 'check out' a numberformat from the cache.
static void releaseNumberFormat(NumberFormat *adopt); // call this function to 'return' the number format to the cache.
Locale fLocale;
UnicodeString fPattern;
// later, allow more than ten items
Format *fFormats[kMaxFormat];
int32_t *fOffsets;
int32_t fCount;
int32_t *fArgumentNumbers;
int32_t fMaxOffset;
/**
* Finds the word s, in the keyword list and returns the located index.
* @param s the keyword to be searched for.
* @param list the list of keywords to be searched with.
* @return the index of the list which matches the keyword s.
*/
static int32_t findKeyword( const UnicodeString& s,
const UChar **list);
/**
* Formats the array of arguments and copies the result into the result buffer,
* updates the field position.
* @param arguments the formattable objects array.
* @param cnt the array count.
* @param status field position status.
* @param recursionProtection Initially zero. Bits 0..9 are used to indicate
* that a parameter has already been seen, to avoid recursion. Currently
* unused.
* @param success the error code status.
*/
UnicodeString& format( const Formattable* arguments,
int32_t cnt,
UnicodeString& result,
FieldPosition& status,
int32_t recursionProtection,
UErrorCode& success) const;
/**
* Checks the segments for the closest matched format instance and
* updates the format array with the new format instance.
* @param position the last processed offset in the pattern
* @param offsetNumber the offset number of the last processed segment
* @param segments the string that contains the parsed pattern segments.
* @param success the error code
*/
void makeFormat( /*int32_t position, */
int32_t offsetNumber,
UnicodeString* segments,
UErrorCode& success);
/**
* Convenience method that ought to be in NumberFormat
*/
NumberFormat* createIntegerFormat(const Locale& locale, UErrorCode& status) const;
/**
* Checks the range of the source text to quote the special
* characters, { and ' and copy to target buffer.
* @param source
* @param start the text offset to start the process of in the source string
* @param end the text offset to end the process of in the source string
* @param target the result buffer
*/
static void copyAndFixQuotes(const UnicodeString& source, int32_t start, int32_t end, UnicodeString& target);
/**
* Converts a string to an integer value using a default NumberFormat object
* which is static (shared by all MessageFormat instances). This replaces
* a call to wtoi().
* @param string the source string to convert with
* @param status the error code.
* @return the converted number.
*/
static int32_t stoi(const UnicodeString& string, UErrorCode& status);
/**
* Converts an integer value to a string using a default NumberFormat object
* which is static (shared by all MessageFormat instances). This replaces
* a call to wtoi().
* @param i the integer to format
* @param string the destination string
* @return a reference to string.
*/
static UnicodeString& itos(int32_t i, UnicodeString& string);
};
inline UClassID
MessageFormat::getDynamicClassID() const
{
return MessageFormat::getStaticClassID();
}
inline UnicodeString&
MessageFormat::format(const Formattable& obj,
UnicodeString& result,
UErrorCode& status) const {
return Format::format(obj, result, status);
}
#endif // _MSGFMT
//eof